JPH05223678A - Pressure/differential pressure transmitter - Google Patents

Abstract

PURPOSE:To provide a pressure/differential pressure transmitter which properly evaluates aged deterioration by eliminating such elements as arising from the difference of calibration environment, although calibration is made in any environment. CONSTITUTION:An intelligent type pressure/differential pressure transmitter is provided with a semiconductor complex sensor 1 which can detect not only pressures of differential pressures but also transmitter temperatures and static pressures at the time of detection. A memory 7 which stares the static pressure and transmitter temperature at calibration (or, only transmitter temperature at calibration) obtained from the semiconductor composite sensor 1, being made to correspond to calibration dates and calibration amount, and a micro processor 4 which outputs the content stored in the memory 7 as required are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure / differential pressure transmitter used for industrial measurement, and particularly, it stores temperature and the like at the time of input calibration or zero static pressure calibration, and stores it over time. The present invention relates to a pressure / differential pressure transmitter that can be properly evaluated.

[0002]

2. Description of the Related Art A pressure / differential pressure transmitter is capable of performing long-term calibration by input calibration (that is, calibration of input / output characteristics such as zero point calibration and span calibration) and zero input static pressure at appropriate intervals. It is used over a period of time. Then, in the conventional transmitter, only the calibration date and time and the calibration amount (for example, the zero point change amount and the span change amount before and after the calibration) are stored at the time of input calibration and static pressure zero calibration.

[0003]

As the accuracy of the pressure / differential pressure transmitter is improved, it is important to select the transmitter that the tendency to strictly control the accuracy is fixed among users and the secular change is small. Has become a factor. Here, in order to correctly evaluate the secular change of the transmitter, it is necessary that each calibration is performed under the environment recommended by the manufacturer, or at least each calibration is under the same environment.

However, there is a case where the secular change cannot be correctly evaluated because the calibration work is not always performed under the environment recommended by the manufacturer. That is, it is rare that the transmitter is removed and calibration work is performed in an instrument room where the environment is stable.In general, calibration work is performed at the site where the equipment is installed. There is a risk that even changes based on will be evaluated as aging.

For example, when the main valve is closed to be isolated from the process, and the calibration is performed by applying an input from the calibration input application port (see FIG. 2), the ambient temperature condition is generally severe at the site where the equipment is installed. In addition, since the influence of the temperature of the process remains depending on the elapsed time after isolation from the process, an unnecessary calibration may be performed. Further, for example, in the differential pressure transmitter, after the process pressure is introduced, the three-valve set is often operated to calibrate the zero point after the static pressure is applied (see FIG. 2). The same can be said of.

The present invention is based on such an actual situation, and even if calibration work is performed in any environment,
An object of the present invention is to provide a pressure / differential pressure transmitter that can properly evaluate secular changes by removing elements based on differences in calibration environments.

[0007]

In order to achieve the above object, the pressure / differential pressure transmitter according to the present invention is capable of detecting the input of pressure or differential pressure, and the transmitter temperature and static pressure at the time of detecting the input. It is an intelligent pressure / differential pressure transmitter equipped with a combined sensor that can also detect the static pressure at the time of calibration and the temperature at the time of calibration or only the temperature at the time of calibration, which is obtained from the combined sensor when input calibration of the device When the static pressure zero calibration of the equipment, the calibration temperature obtained from the composite sensor, the calibration time data storage means for storing the calibration time and the calibration amount, and the stored contents of the calibration time data storage means, Characteristically, it is provided with a calibration data output means for outputting as needed.

[0008]

When the composite sensor detects the pressure or the differential pressure, it simultaneously detects the transmitter temperature and the static pressure at the time of the detection. The calibration data storage means associates the calibration static pressure and the calibration temperature (or only the calibration temperature) obtained from the composite sensor with the calibration date and time or the calibration amount during input calibration or zero static pressure calibration of the device. To remember.

Specifically, at the time of input calibration, the calibration date and time,
In addition to the calibration amount (zero point change amount and span change amount before and after calibration), the transmitter temperature and static pressure value at the time of calibration (however, only the transmitter temperature in the pressure transmitter) are stored. Also, when calibrating the zero of the input static pressure, in addition to the calibration date and time and the calibration amount,
Store the transmitter temperature during calibration in the differential pressure transmitter. The calibration data output means outputs the stored contents of the calibration data storage means as needed. Therefore, the calibration environment (transmitter temperature and static pressure) at the time of calibration can be grasped as necessary. Therefore, when assessing the secular change of equipment, for example, the evaluation should be performed at the same temperature and the same static pressure. Therefore, an element based on the difference in the calibration environment can be removed from the secular change.

[0010]

The present invention will be described in more detail based on the following examples. FIG. 1 is a circuit block diagram of a pressure / differential pressure transmitter according to an embodiment of the present invention. This device includes a semiconductor composite sensor 1 and a pressure sensor 1 _-1 and the temperature sensor 1 _-2 and static pressure sensor 1 _-3, the pressure sensor 1
₁ and receives the output of the temperature sensor 1 _-2 and static pressure sensor 1 _-3, a multiplexer 2 outputs by switching this, an A / D converter 3 for converting the output of the multiplexer 2 into a digital signal, the transmitter originally , A D / A converter 5 for converting pressure / differential pressure data into an analog signal, and a V / I for receiving the output of the D / A converter 5 and converting it into a current output. Converter 6
, A memory 7, 8 for storing a processing program of the microprocessor, data at the time of calibration, etc., and a digital I / O port 9 which operates by transmission and reception with a communicator (not shown).
It consists of and.

FIG. 2 shows a calibration system diagram of the differential pressure transmitter for explaining the process at the time of calibration. Here, the transmitter 10 is a differential pressure transmitter having the configuration of FIG. 1, and is connected to the measurement process via the original valve 11,
The calibration pressure inlet is connected via the calibration valve 12. In addition, 13 is a three valve set,
Reference numeral 4 is a calibration pressure reference device.

In FIG. 2, a DC power supply 15 and a transmitter 10 are provided.
A current loop is formed by, and the output current value is measured by the precision voltmeter 17 as a voltage drop of the precision resistor 16. 18 is a communicator. Next, the operation of the differential pressure transmitter 10 during input calibration will be described with reference to FIG. While measuring the pressure by the pressure reference device 14, the input pressure is applied from the calibration pressure introducing port.
Then, the output current is set to 4. in the state of the input pressure corresponding to 0%.
Adjust to 000mA. Specifically, the output voltage is calibrated to 4.000 mA according to an instruction from the communicator while monitoring the voltage drop with the precision voltmeter 17.

Next, an input pressure corresponding to 100% is applied from the calibration pressure introducing port, and the output current is adjusted to 20.000 mA. Although the zero point and span should have changed due to the above processing, after the calibration is completed, the calibration date and time, the transmitter temperature at the time of calibration, and the static pressure are automatically stored in the memory 7 along with this zero point change and span change. Memorized in. In this way, the transmitter temperature and static pressure are automatically stored as a history corresponding to the calibration date and time, so that the calibrator does not need to bother to measure and record the temperature and static pressure. Therefore, it is very convenient for the proofreader and there is no fear of forgetting the record.

At a later date, for example, when an aging change is to be evaluated, the calibration date and time, the zero point change amount, the span change amount, the static pressure, and the transmitter temperature stored in the memory 7 can be output. Therefore, the zero point change amount and the span change amount can be evaluated including the quality of the calibration environment, and the secular change can be properly evaluated.

[0015]

As described above, in the pressure / differential pressure transmitter according to the present invention, the static pressure during calibration and the temperature during calibration (or only the temperature during calibration) automatically correspond to the calibration date and time and the calibration amount. Be remembered. Since the stored contents can be output arbitrarily, it is possible to reproduce the calibration environment if necessary, and when assessing the secular change of the equipment, remove the element based on the difference of the calibration environment from the secular change. You can make various evaluations.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a pressure / differential pressure transmitter according to an embodiment of the present invention.

FIG. 2 is a diagram showing a calibration system diagram of a differential pressure transmitter.

[Explanation of symbols]

1 composite sensor 2 memory (calibration data storage means) 4 microprocessor (calibration data output means)

Claims (1)

[Claims] 1. A pressure or differential pressure input can be detected, and
An intelligent pressure / differential pressure transmitter equipped with a composite sensor that can also detect transmitter temperature and static pressure when an input is detected. Only temperature or calibration temperature
Further, a calibration-time data storage unit that stores the calibration-time temperature obtained from the composite sensor when the static pressure zero calibration of the device is made to correspond to the calibration date and time, and the storage content of the calibration-time data storage unit. A pressure / differential pressure transmitter, comprising: